A lot of information and knowledge exist about these cars. Here’s my list

Palm Kirbys Experience in a Book. A very comprehensive PDF written by a guy not afraid to challenge Jaguars solutions and suggest improvements. He has owned his 1986 V12 for many tears and the result is 734 pages of knowledge. This is a must read. LINK

Jaguar Repair Operation Manual. Often abbreviated ROM or called the Big Green Book. It a physical book made of real paper, not an internet resource.
Not cheap, but it contains loads of information and instructions. It has paid it self when you have saved one hour in a workshop… LINK

Jaguar S-58 Engine Performance 81-88. Jaguar publication describing the V12 HE Lucas systems. LINK

Parts/Price list from David Manners. LINK

SNG Barratt has a parts catalogue, which is quite old and therefore very good for us PreHE owners. LINK

Jaguarforums XJ-S section. Very active forum with many US-based members. LINK
aguar Enthusiasts Club. UK-based, not a lot of activity. LINK

Link to specific preHE pages and threads in forums:
1978 manual preHE restauration LINK
arry’s Garage drives a 1980 primrose yellow XJ-S from London to Monaco. Youtube
he V12 de-mystified by Ralph Hosier LINK
J-S 1976-1991 US judging guide. Lots of details on originality LINK

Model history:
XJ-S development history LINK
Ed Abbott, working at Jaguar 1970-1985 in the Experimental Road Test department tells his story about the XJ27 development: LINK